Improved handling of git syntax names with no git repository

This makes "is_git_repository()" return non-NULL for all file names that
match the git name pattern, even if we don't find an actual git
repository there.  That way, we won't fall back to writing out an XML
file with an odd filename.

If there is no actual git repository, we return a special invalid dummy
pointer, and then the git reading and writing routines will catch it and
return the appropriate error.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

3 files changed, 30 insertions, 6 deletions

diff --git a/dive.h b/dive.h
index c6867fc5d..c91fb03e4 100644
--- a/dive.h
+++ b/dive.h
@@ -689,6 +689,7 @@ extern int export_dives_uddf(const char *filename, const bool selected);
 
 struct git_oid;
 struct git_repository;
+#define dummy_git_repository ((git_repository *) 3ul) /* Random bogus pointer, not NULL */
 extern struct git_repository *is_git_repository(const char *filename, const char **branchp);
 extern int git_save_dives(struct git_repository *, const char *, bool select_only);
 extern int git_load_dives(struct git_repository *, const char *);
diff --git a/load-git.c b/load-git.c
index c861799b4..4040c1677 100644
--- a/load-git.c
+++ b/load-git.c
@@ -1243,7 +1243,11 @@ static int do_git_load(git_repository *repo, const char *branch)
  */
 int git_load_dives(struct git_repository *repo, const char *branch)
 {
-	int ret = do_git_load(repo, branch);
+	int ret;
+
+	if (repo == dummy_git_repository)
+		return report_error("Unable to open git repository at '%s'", branch);
+	ret = do_git_load(repo, branch);
 	git_repository_free(repo);
 	free((void *)branch);
 	finish_active_dive();
diff --git a/save-git.c b/save-git.c
index 745f26b01..74eab55bb 100644
--- a/save-git.c
+++ b/save-git.c
@@ -924,30 +924,45 @@ struct git_repository *is_git_repository(const char *filename, const char **bran
 	if (!flen)
 		return NULL;
 
+	/*
+	 * This is the "point of no return": the name matches
+	 * the git repository name rules, and we will no longer
+	 * return NULL.
+	 *
+	 * We will either return "dummy_git_repository" and the
+	 * branch pointer will have the _whole_ filename in it,
+	 * or we will return a real git repository with the
+	 * branch pointer being filled in with just the branch
+	 * name.
+	 *
+	 * The actual git reading/writing routines can use this
+	 * to generate proper error messages.
+	 */
+	*branchp = filename;
 	loc = malloc(flen+1);
 	if (!loc)
-		return NULL;
+		return dummy_git_repository;
 	memcpy(loc, filename, flen);
 	loc[flen] = 0;
 
 	branch = malloc(blen+1);
 	if (!branch) {
 		free(loc);
-		return NULL;
+		return dummy_git_repository;
 	}
 	memcpy(branch, filename+flen+1, blen);
 	branch[blen] = 0;
 
 	if (stat(loc, &st) < 0 || !S_ISDIR(st.st_mode)) {
 		free(loc);
-		return NULL;
+		return dummy_git_repository;
 	}
 
 	ret = git_repository_open(&repo, loc);
 	free(loc);
 	if (ret < 0) {
 		free(branch);
-		return NULL;
+		return dummy_git_repository;
 	}
 	*branchp = branch;
 	return repo;
@@ -955,7 +970,11 @@ struct git_repository *is_git_repository(const char *filename, const char **bran
 
 int git_save_dives(struct git_repository *repo, const char *branch, bool select_only)
 {
-	int ret = do_git_save(repo, branch, select_only);
+	int ret;
+
+	if (repo == dummy_git_repository)
+		return report_error("Unable to open git repository '%s'", branch);
+	ret = do_git_save(repo, branch, select_only);
 	git_repository_free(repo);
 	free((void *)branch);
 	return ret;